Thank you for taking the time to report this bug and helping to make Ubuntu better. It seems that your bug report is not filed about a specific source package though, rather it is just filed against Ubuntu in general. It is important that bug reports be filed about source packages so that people interested in the package can find the bugs about it. You can find some hints about determining what package your bug might be about at https://wiki.ubuntu.com/Bugs/FindRightPackage. You might also ask for help in the #ubuntu-bugs irc channel on Freenode.

I am having the same problem. I've been using 11.04 until now, since it supported my three monitor setup (with 2 nvidia cards).

Hopeful that multi monitor configurations had been fixed in 12.04 I took the chance and upgraded. Unfortunately, the only way I can get the three monitors to work simultaneously is using the nvidia proprietary driver and xinerama. (With 11.04 it worked with separate X screens, but that failes in 11.10 and 12.04).

With Xinerama, the theme is not applied to all the windows - like in the image linked in the bug description - and of course compiz is out of the question but that's another story...